This is the fourth edition of the ground-breaking Chilling Prospects series of SEforALL, which tracks immediate vulnerability due to a lack of access to cooling. The work identifies populations at risk for whom a lack of access to cooling threatens their immediate health and safety. It models risk based on a spectrum of cooling needs: human comfort and safety; agriculture, food and nutrition security; and health services and medicine. On this basis, it categorizes risk across four populations: the rural poor, the urban poor, the lower-middle income and the middle income.